At present, in order to effectively use the mobile network resources, the 3rd Generation Partnership Project (referred to as 3GPP) proposes a service of Multimedia Broadcast and Multicast Service (referred to as MBMS), which can achieve the point-to-multipoint service from one data source to multiple targets.
In the Long Term Evolution (referred to as LTE) system, the data channel and the control channel of the MBMS service can employ a single-cell transmitting mode and a multi-cells transmitting mode. The single-cell transmitting mode indicates that the control channel and the data channel of the MBMS service are only transmitted in present cell, and there is no Multicast Broadcast Single Frequency Network (referred to as MBSFN) macro diversity function; while the multi-cells transmitting mode indicates that multiple cells transmit the same data in the same time-frequency resources, viz. the MBMS service or control information employs a content synchronization manner, viz. employing the MBSFN macro diversity. Through the multi-cells transmitting mode, multiple cells transmit data or control signaling of the MBMS service of the same contents at the same time, which can improve the receiving gain of the User Equipment (referred to as UE).
Multicast Channel (referred to as MCH) is a transmission channel adapted for the point-to-multipoint transmission, and its corresponding physical resources are multicast resources allocated by the system for the transmission of the MBMS service. One carrier frequency can bear multiple MCHs. The physical channel bearing particular MCH is determined by a set of subframes of patterns. These frames may not be continuous in time, the pattern is referred to as an MCH subframe allocation pattern (referred to as MSAP), and each MSAP describes the physical resources of one MCH channel. In the LTE system, the multicast resources of each MBSFN region can be divided in the unit of subframe according to certain patterns. The resources indicated by each pattern constitute one MCH. Multicast Traffic Channel (referred to as MTCH) is a logical channel. One MTCH bears the data of one or more services, and one service is only beared in one MTCH. The MTCH is mapped to the MCH for transmission, and one or more MTCHs can be mapped to one or more MCHs, viz. multiple MBMS services can be mapped to one MCH.
The features of employing the multi-cells transmitting mode for the MBMS transmission comprise: synchronous transmission in the MBSFN region; supporting multi-cells MBMS transmission data combination; mapping MTCH and MCCH to MCH transmission channel in the p-T-m mode, etc.
Through the MSAP information, the UE can acquire the specific multicast resources corresponding to a specific MCH. However, as the MCH contains the data of one or more MBMS services (for example, one or more MTCHs), it is necessary to specify, through the MBMS dynamic schedule information, the specific physic resources corresponding to a certain MBMS service, so that, when the UE receives a particular MBMS service, the UE can acquire the exact resources of the MBMS service through the indication of the MBMS dynamic schedule information, so as to achieve accurate receiving and save the energy consumption of the UE.
Currently, in the LTE network, there exist two subframe structures, namely unicast subframe and MBSFN subframe structures. The two subframe structures are both further divided based on Orthogonal Frequency Division Multiplexing (referred to as OFDM) symbol in time domain. In order to reduce inter-symbol interference, the two subframe structures are respectively added with a cyclic prefix (referred to as CP) in the OFDM symbol time domain. At present, in the case of 15 KHz subcarrier interval, there are two CPs in all, viz. a Normal cyclic prefix and an Extended cyclic prefix. As the time length of the extended CP is greater than that of the normal CP, therefore in one subframe, if extended CP is configured, there are a total of 12 OFDM symbols, as shown in FIG. 1A, and if normal CP is configured, there are a total of 14 OFDM symbols, as shown in FIG. 1B. Specifically: 1. normal CP, for the OFDM symbol with number 0, the length TCP=160×Ts, and for the OFDM symbols with number 1 to 6, the length TCP=144×Ts; 2. extended CP, for the OFDM symbols with number 0 to 5, the length TCP-e=512×Ts, wherein Ts= 1/30720 ms.
In the current protocol, the configuration of the MBSFN subframe structure requires that the first one or two OFDM symbols in the MBSFN subframes are reserved as non-MBSFN symbols for the non-MBSFN transmission, and the one or two non-MBSFN symbols employ the same CP configuration as the subframe of number 0, viz. it may be either a normal CP or an extended CP. The MBSFN transmission is carried out in the rest OFDM symbols in the MBSFN subframes. These OFDM symbols are referred to as MBSFN symbols, and in order to facilitate the realization of synchronization and macro diversity, the extended CP configuration is adapted for the MBSFN symbols. Moreover, when the non-MBSFN symbols employ the normal CP configuration, an essential protection time gap is needed between the non-MBSFN symbols and the MBSFN symbols, as shown in FIG. 2A; and when the non-MBSFN symbols employ the extended CP configuration, no protection time gap is needed between the non-MBSFN symbols and the MBSFN symbols, as shown in FIG. 2B. For the MBSFN subframes, the user who does not receive the MBMS service only performs receiving on the first one or two OFDM symbols of the MBSFN subframes, but does not perform receiving on other OFDM symbols.
In the related art, the resources under the scheduling/domination of the MBMS dynamic schedule information are defined in time length as schedule period, such as 320 ms, 640 ms and so on. FIG. 3A and FIG. 3B are schematic diagrams of the logical relation between the setting of the existing schedule block in a schedule period and the MBMS service. FIG. 3B shows the subframes such as subframe 0, subframe 4, subframe 5 and subframe 9, which the protocol stipulates that cannot be adapted for carrying the MBMS service. As shown in FIG. 3A and FIG. 3B, the network side is configured with the allocation information of multicast subframes, wherein the schedule block contains the schedule information of all the services in the schedule period, the schedule block is transmitted at the most initial position of the entire schedule period, and the range of the schedule resources is all the MBMS services in the schedule period. The most initial position can be the first multicast subframe or the corresponding physical resources in the schedule period.
For the network side, the configuration of the multicast subframe resources for transmitting the MBMS service is carried out by semi-static configuration according to the MBMS service volume of the current system bearer. As the semi-static configuration has the features of slow variation and uniformization of resource allocation, while the service data volume of the MBMS service has the features of fast variation and burst, the inconsistent features between the two would possibly lead to mismatching between the resource allocation and the data volume to be transmitted, which is usually reflected in the occurrence of over-allocation multicast subframes in a dynamic schedule period. Since the over-allocation multicast subframes do not bear the MBMS service, and thus the unicast users only receive data of unicast control region of multicast subframes, the over-allocation multicast subframes neither bear a multicast service nor bear a unicast service, which results in the waste of the radio resources, and reduces the utilization rate of the radio resources.